The incidence of foliar plant pathogens has increased in recent years, and the cost of managing foliar plant diseases has inflated field production costs. In particular, seed corn fields have encountered numerous plant pathologic problems. The increased incidence of plant pathogens has brought about the need for treating seed fields with foliar fungicides such as TILT.RTM..
Research indicates that seed field yield losses from foliar diseases can reach as high as 58% if infection occurs early and environmental conditions favor disease spread and development. Early detection and diagnosis of the disease with timely applications of a foliar fungicide are necessary to avoid such devastating losses. Rapid diagnosis of plant pathogens is also critical because some fungicides cannot be applied after a certain stage in the plant's maturity. In addition, some genetic leaf abnormalities (e.g., lesion mimics, leaf speckling, heat stripe, genetic stripe) look similar to symptoms produced by plant pathogens. A misdiagnosis of a genetic abnormality as a plant pathogen can be very costly--one application of TILT.RTM. will typically cost $15.00-$16.00/acre.
With respect to corn, Gray Leaf Spot (Cercospora zeae-maydis) is now the leading plant pathogen found in seed corn fields, and the spread of Gray Leaf Spot throughout U.S. seed corn production locations has increased substantially over the past several years. Early detection and identification of Gray Leaf Spot in seed corn fields is essential to reverse this trend and suppress this plant pathogen.
Accurate identification of plant pathogens within a field has typically been done by an agronomist with support from a plant pathology laboratory. In most situations, however, a plant pathologist is not on-site at a seed crop production location. Moreover, most seed crop production locations are at a distance from facilities that specialize in the identification of plant pathogens. This distance between the field site and the diagnostician creates a significant increase in turn-around and response times. Plant or pathogen samples must be sent from the seed crop production location to the plant pathology diagnostic laboratory by transportation or mail. Samples routinely take 1-4 days to arrive at the laboratory. An additional 2-7 days are needed for analysis and 1-3 more days for response. At best, a diagnosis takes four days, and at worst, fourteen days or more. More recently, with overnight delivery and electronic mail, analysis times have fallen to the range of 3-5 days. However, there are significant problems attendant to transporting or shipping diseased plant material over long distances, in particular, across state or national borders.
In addition to the need for faster turn-around times for sample analysis, the need to provide pathology support on a global scale has increased. U.S. Pat. Nos. 5,216,596 and 5,297,034 to Weinstein disclose telepathology diagnostic systems whereby a diagnostician can evaluate animal tissue specimens at a remote site and make a diagnosis therefrom. The present invention meets a need in the art for plant disease diagnosis at remote sites.